allow unit test of extra-components

Merges https://github.com/espressif/esp-idf/pull/5345

tools/unit-test-app/CMakeLists.txt

@@ -2,8 +2,10 @@
 # CMakeLists in this exact order for cmake to work correctly
 cmake_minimum_required(VERSION 3.5)
 
-set(EXTRA_COMPONENT_DIRS "$ENV{IDF_PATH}/examples/cxx/experimental/experimental_cpp_component/"
-                         "$ENV{IDF_PATH}/examples/peripherals/rmt/ir_protocols/components")
+set(EXTRA_COMPONENT_DIRS
+    ${EXTRA_COMPONENT_DIRS}
+    "$ENV{IDF_PATH}/examples/cxx/experimental/experimental_cpp_component/"
+    "$ENV{IDF_PATH}/examples/peripherals/rmt/ir_protocols/components")
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 project(unit-test-app)